Thursday, July 30, 2009

Replacing Gasoline with Natural Gas: How Much do we Have

Robert Rapier writing at The Oil Drum:
You may have seen the recent news that a report by the Potential Gas Committee says natural gas reserves in 2008 rose to 2,074 trillion cubic feet. The New York Times and the Wall Street Journal (via Rigzone) both had stories on it, and T. Boone Pickens issued a press release. In this post, I will look at how long these reserves might last, if used to replace US gasoline usage....

...A number of people have rightly pointed out that a 100-year supply implies usage at current rates. But it got me to thinking about how much natural gas it would take to displace all U.S. gasoline consumption. So in the spirit of my year-ago essay Replacing Gasoline with Solar Power, I will do the same calculation for replacing gasoline with natural gas. The big difference between this calculation and the earlier one is that solar power still has some technical issues to resolve (e.g., storage) and electric vehicles are not yet ready for prime time. On the other hand we are perfectly capable, today, of displacing large numbers of gasoline-fueled vehicles with natural gas.

How Much Do We Need?

The U.S. currently consumes 390 million gallons of gasoline per day. (Source: EIA). A gallon of gasoline contains about 115,000 BTUs. (Source: EPA). The energy content of this much gasoline is equivalent to 45 trillion BTUs per day. The energy content of natural gas is about 1,000 BTUs per standard cubic foot (scf). Therefore, to replace all gasoline consumption would require 45 billion scf per day, or 16.4 trillion scf per year. Current U.S. natural gas consumption is 23 trillion scf per year (Source: EIA). Therefore, replacing all gasoline consumption with natural gas would require a total usage of 39.4 trillion scf per year, an increase in natural gas consumption of 71% over present usage.

Assuming for the sake of argument that the 2,074 trillion standard cubic feet cited in the study is accurate, that the "probable, possible and speculative reserves" eventually equate to actual reserves, and that the gas is economically recoverable, that is enough gas for 53 years of combined current natural gas consumption and gasoline consumption. If you assume that only the proven plus probable reserves are eventually recovered, the amount drops to about 1/3rd of the 2,074 trillion scf estimate, still enough to satisfy current natural gas consumption and replace all gasoline consumption for almost 20 years.

We can also calculate in terms of oil imports. Right now the U.S. imports about 13 million barrels per day of all petroleum products. A barrel of oil contains around 5.8 million BTUs, but oil only makes up 10 million of the 13 million barrel per day figure. Other imports include things like gasoline (4.8 million BTUs/bbl) and ethanol (3.2 million BTUs/bbl). Scanning the list of imports, I probably won't be too far off the mark to presume that the average BTU value of those 13 million bpd of imports is about 5.4 million BTUs/bbl. On an annual basis, this equates to 25.6 trillion scf of natural gas, which would be an increase over current natural gas usage of 111%. Going back to the 2,074 trillion scf from the study, this would be enough to displace imports of all petroleum products (again, at current usage rates and not factoring in declining U.S. oil production) for 43 years.

What's the Cost?

Natural gas is presently trading at about $4 per million (MM) BTU (although December 2009 is trading at almost $6). Oil is presently trading at $71/bbl, which equates to $12.24/MMBTU. Gasoline is presently trading at over $17/MMBTU. Thus, natural gas is a bargain relative to oil or gasoline. Incidentally, I just checked on seasoned wood and wood pellets, and they range from $8-$12/MMBTUs. So it is cheaper to heat your house with gas than with wood. I am not sure I would have guessed that.

While natural gas is a bargain relative to gasoline, converting a gasoline-powered vehicle to natural gas isn't cheap. According to this source, it can cost $12,500 to $22,500 to convert a gasoline-powered car to natural gas....MORE